Latin American Trans-ancestry INitiative for OCD genomics (LATINO): Study protocol

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder. Worldwide, its prevalence is ~2% and its etiology is mostly unknown. Identifying biological factors contributing to OCD will elucidate underlying mechanisms and might contribute to improved treatment outcomes. Genomic studies of OCD are beginning to reveal long-sought risk loci, but >95% of the cases currently in analysis are of homogenous European ancestry. If not addressed, this Eurocentric bias will result in OCD genomic findings being more accurate for individuals of European ancestry than other ancestries, thereby contributing to health disparities in potential future applications of genomics. In this study protocol paper, we describe the Latin American Trans-ancestry INitiative for OCD genomics (LATINO, https://www.latinostudy.org). LATINO is a new network of investigators from across Latin America, the United States, and Canada who have begun to collect DNA and clinical data from 5000 richly phenotyped OCD cases of Latin American ancestry in a culturally sensitive and ethical manner. In this project, we will utilize trans-ancestry genomic analyses to accelerate the identification of OCD risk loci, fine-map putative causal variants, and improve the performance of polygenic risk scores in diverse populations. We will also capitalize on rich clinical data to examine the genetics of treatment response, biologically plausible OCD subtypes, and symptom dimensions. Additionally, LATINO will help elucidate the diversity of the clinical presentations of OCD across cultures through various trainings developed and offered in collaboration with Latin American investigators. We believe this study will advance the important goal of global mental health discovery and equity.

Investigating the association of anxiety disorders with heart rate variability measured using a wearable device

BACKGROUND

Reduced vagally-mediated heart rate variability (HRV) has been associated with anxiety disorders (AD). The aim of this study was to use a wearable device and remote study design to re-evaluate the association of HRV with ADs, anxiety-related traits, and confounders.

METHODS

240 individuals (AD = 120, healthy controls = 120) completed an at-home assessment of their short-term resting vagally-mediated HRV using a wristband, monitored over videoconference. Following quality control, analyses were performed investigating differences in HRV between individuals with AD (n = 119) and healthy controls (n = 116), associations of HRV with anxiety-related traits and confounders, and antidepressants effects on HRV in patients, including analyses stratified by ancestry (i.e., European, East Asian, African).

RESULTS

Among the confounders investigated, only age had a significant association with HRV. Patients with an AD had significantly lower vagally-mediated HRV than healthy controls in the European subsample, with a trend of significance in the whole sample. HRV was significantly associated with the Hamilton Anxiety Rating Scale (HAM-A) but not with antidepressant use in the European subsample.

LIMITATIONS

The study measures occurred in a non-standardized at-home setting, and the three ancestry group sample sizes were unequal.

CONCLUSIONS

This study demonstrates reduced vagally-mediated HRV among patients with ADs compared to healthy controls. Results also point to low HRV being related to more physical anxiety symptoms (measured via HAM-A), suggesting a possible anxiety subtype. Overall, this study highlights the feasibility of using wearables for patients and encourages exploration of the biological and clinical utility of HRV as a risk factor for ADs.

Genome-wide association study identifies 30 obsessive-compulsive disorder associated loci

Obsessive-compulsive disorder (OCD) affects ~1% of the population and exhibits a high SNP-heritability, yet previous genome-wide association studies (GWAS) have provided limited information on the genetic etiology and underlying biological mechanisms of the disorder. We conducted a GWAS meta-analysis combining 53,660 OCD cases and 2,044,417 controls from 28 European-ancestry cohorts revealing 30 independent genome-wide significant SNPs and a SNP-based heritability of 6.7%. Separate GWAS for clinical, biobank, comorbid, and self-report sub-groups found no evidence of sample ascertainment impacting our results. Functional and positional QTL gene-based approaches identified 249 significant candidate risk genes for OCD, of which 25 were identified as putatively causal, highlighting WDR6, DALRD3, CTNND1 and genes in the MHC region. Tissue and single-cell enrichment analyses highlighted hippocampal and cortical excitatory neurons, along with D1- and D2-type dopamine receptor-containing medium spiny neurons, as playing a role in OCD risk. OCD displayed significant genetic correlations with 65 out of 112 examined phenotypes. Notably, it showed positive genetic correlations with all included psychiatric phenotypes, in particular anxiety, depression, anorexia nervosa, and Tourette syndrome, and negative correlations with a subset of the included autoimmune disorders, educational attainment, and body mass index.. This study marks a significant step toward unraveling its genetic landscape and advances understanding of OCD genetics, providing a foundation for future interventions to address this debilitating disorder.

Online versus in-person delivery of cognitive behaviour therapy for obsessive compulsive disorder: An examination of effectiveness

Cognitive behavioural therapy (CBT) including exposure and response prevention is the first-line psychological treatment for obsessive compulsive disorder (OCD). Given changes in the clinical landscape, there are increasing efforts to evaluate its effectiveness in online contexts. Mirroring the traditional in-person delivery, few studies have assessed the role of therapist-guided, manual-based CBT for OCD delivered in real-time via videoconferencing methods. The present study sought to fill this gap by comparing in-person and online delivery of group-based CBT for the treatment of OCD. A convenience sample of participants with moderate to severe OCD (n = 144) were recruited from a naturalistic database from two large OCD specialty assessment and treatment centres. Patients received group-based CBT that was provided in-person (pre-COVID-19 pandemic; March 2018 to March 2020) or online via videoconferencing (during the COVID-19 pandemic; March 2020 to April 2021). In both delivery methods, treatment consisted of 2-h weekly sessions led by trained clinicians. Analyses revealed that, regardless of treatment modality, both in-person and online groups demonstrated significant, reliable, and statistically equivalent improvements in OCD symptoms post-treatment. Videoconferenced, clinician-led CBT may be a promising alternative to in-person delivery for those with moderate to severe OCD symptoms.

The effect of aerobic exercise alone and in combination with cognitive behavioural therapy on obsessive compulsive disorder: A randomized control study

PURPOSE

Cognitive behavioural therapy (CBT) has been found to be an effective treatment for OCD, but there remains a significant proportion of individuals who fail to show a treatment response. Aerobic exercise has previously been associated with decreases in anxiety and depression, as well as improvements in OCD symptoms in small-scale studies. The purpose of the present research was to use a randomized control trial design to examine the effects of exercise alone and in combination with CBT, on OCD symptoms and secondary symptoms.

METHOD

125 participants were randomly assigned to one of four treatment groups: waitlist control, exercise, CBT, and CBT with exercise. OCD symptom severity was measured at four points over the course of treatment, secondary outcome measures were gathered at three points over treatment.

RESULTS

CBT alone and combined with exercise was associated with significantly greater OCD symptom reduction than exercise alone or the control groups. Total exercise frequency predicted OCD symptom reduction in the groups in which exercise was measured. Group membership did not significantly predict reductions in secondary outcome measures.

CONCLUSION

Exercise frequency, rather than the presence or absence of exercise, appears to predict OCD symptom reduction, as did participation in CBT.

White matter volume and myelin oligodendrocyte glycoprotein (MOG) microsatellites in pediatric obsessive-compulsive disorder

The myelin oligodendrocyte glycoprotein ( MOG ) gene plays an important role in myelination and has been implicated in the genetics of white matter changes in obsessive-compulsive disorder (OCD). We examined the association between variations of two microsatellite markers across MOG for association and total white matter volume as measured using volumetric MRI in 37 pediatric OCD patients 7-18 years. We compared white matter volumes between microsatellite allele groups using analysis of covariance with covariates of age, gender, and total intracranial volume. After controlling for multiple comparisons, a significant relationship was detected between MOG (TAAA)n and increased total white matter volume ( P  = 0.018-0.028). Although preliminary, our findings provide further support for the involvement of MOG in OCD.

Systematic Review and Meta-Analysis of the Placebo Effect and its Correlates in Obsessive Compulsive Disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a major mental health condition with a lifetime prevalence rate of 1.3% among adults. While placebo effects are well described for conditions such as depressive and anxiety disorders, they have not been systematically characterized in OCD.

OBJECTIVES

We aimed to determine the impact of placebos in improving different symptom domains in patients with OCD.

METHODS

We systematically searched PubMed, EMBASE, Scopus, Web of Science, Ovid, the Cochrane Library, and Google Scholar databases/search engine from inception to January 2021 for randomized controlled trials of treatments for OCD with a placebo arm. A modified Cohen's effect size (ES) was calculated using change in baseline to endpoint scores for different measurement scales within placebo arms to estimate placebo effects and to investigate their correlates by random-effects model meta-analyses.

RESULTS

Forty-nine clinical trials (placebo group n  =  1993), reporting 80 OCD specific (153 measures in general) were included in the analysis. Overall placebo ES (95% confidence interval [CI]) was 0.32 (0.22-0.41) on OCD symptoms, with substantial heterogeneity (I-square = 96.1%). Among secondary outcomes, general scales, ES: 0.27 (95%CI: 0.14-0.41), demonstrated higher ES than anxiety and depression scales, ES: 0.14 (95%CI: -0.4 to 0.32) and 0.05 (95%CI: -0.05 to 0.14), respectively. Clinician-rated scales, ES: 0.27(95%CI: 0.20-0.34), had a higher ES than self-reported scales, ES: 0.07 (95%CI: -0.08 to 0.22). More recent publication year, larger placebo group sample size, shorter follow-up duration, and younger age of participants were all associated with larger placebo ES. Egger's test reflected possible small-study effect publication bias (P  =  0.029).

CONCLUSION

Placebo effects are modest in OCD trials and are larger in clinician ratings, for younger patients, and early in the treatment course. These findings underscore the need for clinicians and scientists to be mindful of placebo effects when formulating treatments or research trials for OCD.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42019125979.

Latin American Trans-ancestry INitiative for OCD genomics (LATINO): Study Protocol

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder. Worldwide, its prevalence is ~2% and its etiology is mostly unknown. Identifying biological factors contributing to OCD will elucidate underlying mechanisms and might contribute to improved treatment outcomes. Genomic studies of OCD are beginning to reveal long-sought risk loci, but >95% of the cases currently in analysis are of homogenous European ancestry. If not addressed, this Eurocentric bias will result in OCD genomic findings being more accurate for individuals of European ancestry than other ancestries, thereby contributing to health disparities in potential future applications of genomics. In this study protocol paper, we describe the Latin American Trans-ancestry INitiative for OCD genomics (LATINO, www.latinostudy.org). LATINO is a new network of investigators from across Latin America, the United States, and Canada who have begun to collect DNA and clinical data from 5,000 richly-phenotyped OCD cases of Latin American ancestry in a culturally sensitive and ethical manner. In this project, we will utilize trans-ancestry genomic analyses to accelerate the identification of OCD risk loci, fine-map putative causal variants, and improve the performance of polygenic risk scores in diverse populations. We will also capitalize on rich clinical data to examine the genetics of treatment response, biologically plausible OCD subtypes, and symptom dimensions. Additionally, LATINO will help elucidate the diversity of the clinical presentations of OCD across cultures through various trainings developed and offered in collaboration with Latin American investigators. We believe this study will advance the important goal of global mental health discovery and equity.

Characterizing the content, messaging, and tone of trichotillomania on YouTube: A content analysis

BACKGROUND

Trichotillomania is associated with secrecy and reluctance to seek help due to shame and lack of knowledge. Social media can connect people with similar lived experience. However, there is no literature regarding online communities related to trichotillomania. This study is a content analysis of depictions of trichotillomania on YouTube to identify the potential role of social media in this disorder.

METHODS

We used a cross-sectional observational study to examine the 100 most-viewed YouTube videos for trichotillomania content until June 2018. Up to 96 variables were abstracted from each video including demographics, characteristics of the videos, and depictions of trichotillomania.

RESULTS

View counts ranged from 9,186 to 15,597,149. Uploaders had a mean age of 20.1 years, were mostly female (85%) and appearing Caucasian (63%). Nearly half of the videos were self-filmed stories (48%). Most had a neutral message (44%), provided strategies to stop hair-pulling (31%), or focused on stimulating discussion (17%). Approximately half had a factual tone (51%) and many were hopeful (44%). Videos accurately described hair-pulling and associated characteristics.

LIMITATIONS

This study was limited to an analysis of video content. Future research should examine the comments on the videos as well as other social media platforms. It may also be important to assess the socioeconomic status of video uploaders and ensure the broader accessibility of positive messages on trichotillomania.

CONCLUSIONS

People with trichotillomania may find positive messages, information, and helpful recommendations on YouTube. This may represent an under-leveraged venue to improve clinical outcomes for people with trichotillomania.

A narrative review of exercise and obsessive-compulsive disorder

OBJECTIVE

Individuals with obsessive-compulsive disorder (OCD) suffer significant distress due to their condition; however, there can be multiple barriers to treatment. Even following OCD-tailored treatment, symptoms often remain. Exercise may be an effective and available approach to managing OCD, and yet, there are no specifically dedicated reviews, limiting integration into clinical practice. This study aimed to provide an overview of the literature on exercise and OCD.

METHOD

Four databases, the Cochrane Central Register of Controlled Trials, MEDLINE, PsycINFO, and EMBASE, were systematically searched. 1534 records were screened and the reference lists of eligible articles were examined. For this review, 11 extracted studies were narratively explored.

RESULTS

Two observational and nine interventional studies were included, of which one article focused on youth and ten studies focused on adults. Physical activity likely reduces the risk of metabolic syndrome or general health conditions. Several pre-post studies demonstrated exercise's benefits for OCD symptoms, while the only randomized controlled trial showed negative findings for its efficacy in reducing obsessions and compulsions.

CONCLUSIONS

The evidence for aerobic exercise's long-term benefits for the symptoms of OCD is mixed, but remains promising. Potential mechanisms of exercise's effects and future directions for research are explored.

An association of Myelin Oligodendrocyte Glycoprotein (MOG) gene variants with white matter volume in pediatric obsessive-compulsive disorder

An increasing number of neuroimaging studies have implicated alterations of white matter in obsessive-compulsive disorder (OCD). The myelin oligodendrocyte glycoprotein (MOG) gene plays a major role in myelination, and has previously demonstrated significant association with this disorder, thus variations in this gene may contribute to observed white matter alterations. The purpose of this study is to examine the relationship between white matter volume in OCD and genetic variations in the MOG gene. Two polymorphisms in the MOG gene, MOG(C1334T) and MOG(C10991T), were investigated for association with total white matter volume as measured using volumetric magnetic resonance imaging in 37 pediatric OCD patients. We compared white matter volumes between allele and genotype groups for each polymorphism using ANCOVA. A significant relationship was detected between genotype C/C of MOG(C10991T) and decreased total white matter volume (P = 0.016). Our results showed an association between a MOG genetic variant and white matter volume. This finding is intriguing in light of the posited role of white matter alteration in the etiology of at least some cases of childhood-onset OCD. Further investigation with larger samples and sub-regional white matter volume phenotypes is warranted.

Effectiveness of intensive treatment services for obsessive compulsive disorder: outcomes from the first Canadian residential treatment program

Background: Obsessive-Compulsive Disorder (OCD) is a psychiatric illness that can result in debilitating symptoms and functional impairment. Until recently, individuals with severe OCD symptoms have not received appropriate services within the Canadian healthcare system. The Frederick W. Thompson Anxiety Disorders Centre launched an Intensive Services Residential treatment programme for OCD in July 2017 to meet the needs of the Canadian population. This paper sets out to demonstrate the effectiveness of this programme.Methods: This study incorporated quantitative and qualitative data collection. Quantitative data were analysed using paired sample t-tests while qualitative data was transcribed and coded for emerging themes.Results: Beneficial changes in symptomatology were found. Client narrative emphasised the importance of exposure response prevention (ERP), creation of an OCD community as well as enhanced functionality in clients' lives. Clients also commented on why they believed the treatment worked and points of potential improvement for discharge planning and programme organisation.Conclusions: This study adds to the growing body of evidence regarding the importance of intensive services for individuals experiencing severe symptoms of OCD. Enhancing accessibility to services and ensuring ongoing maintenance of gains will be important next steps in ensuring long-term recovery for individuals with severe symptoms of OCD.Key pointsIntensive services treatment for OCD has been found to be beneficial for clients and this paper demonstrates the first time this has been seen within a Canadian programme.Treatment provided decreased OCD severity and increased functionality and quality of life.Clients cited exposure and response prevention work as a key ingredient in their recovery.Our programme is always in an ongoing state of quality improvement, ensuring client engagement and satisfaction.

Towards precision medicine in generalized anxiety disorder: Review of genetics and pharmaco(epi)genetics

Generalized anxiety disorder (GAD) is a prevalent and chronic mental disorder that elicits widespread functional impairment. Given the high degree of non-response/partial response among patients with GAD to available pharmacological treatments, there is a strong need for novel approaches that can optimize outcomes, and lead to medications that are safer and more effective. Although investigations have identified interesting targets predicting treatment response through pharmacogenetics (PGx), pharmaco-epigenetics, and neuroimaging methods, these studies are often solitary, not replicated, and carry several limitations. This review provides an overview of the current status of GAD genetics and PGx and presents potential strategies to improve treatment response by combining better phenotyping with PGx and improved analytical methods. These strategies carry the dual benefit of delivering data on biomarkers of treatment response as well as pointing to disease mechanisms through the biology of the markers associated with response. Overall, these efforts can serve to identify clinical, genetic, and epigenetic factors that can be incorporated into a pharmaco(epi)genetic test that may ultimately improve treatment response and reduce the socioeconomic burden of GAD.

Pharmacogenetic evaluation of a DISP1 gene variant in antidepressant treatment of obsessive-compulsive disorder

OBJECTIVES

A recent genome-wide association study (GWAS) in obsessive-compulsive disorder (OCD) reported a significant marker in the dispatched homolog 1 (Drosophila) gene (DISP1 gene) associated with serotonin reuptake inhibitor (SRI) antidepressant response (Qin et al., ). DISP1 has never been examined before in terms of association with SRI response until this GWAS. We attempt to replicate the GWAS finding by investigating the association of the DISP1 rs17162912 polymorphism with SRI response in our sample of 112 European Caucasian OCD patients.

METHODS

Patients were previously treated naturalistically with up to 6 different SRIs sequentially, including 5 selective SRIs (fluoxetine, fluvoxamine, sertraline, paroxetine, and citalopram) and 1 SRI (clomipramine). Each medication trial was evaluated retrospectively for response and was rated categorically as either responder or nonresponder using the Clinical Global Impression-Improvement scale. Fisher's exact test was used to investigate the relationship between the DISP1 rs17162912 genotype distribution and SRI response.

RESULTS

We did not observe a significant association between rs17162912 and SRI response (p = .32).

CONCLUSION

This replication study did not support the role of DISP1 in predicting SRI response in OCD; however, methodological differences between the original GWAS and our study, as well as limited power and low minor allele frequency, may have hindered replication.

Analysis of shared heritability in common disorders of the brain

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

Investigating Cortical Inhibition in First-Degree Relatives and Probands in Schizophrenia

Deficits in GABAergic inhibitory neurotransmission are a reliable finding in schizophrenia (SCZ) patients. Previous studies have reported that unaffected first-degree relatives of patients with SCZ demonstrate neurophysiological abnormalities that are intermediate between probands and healthy controls. In this study, first-degree relatives of patients with SCZ and their related probands were investigated to assess frontal cortical inhibition. Long-interval cortical inhibition (LICI) was measured from the dorsolateral prefrontal cortex (DLPFC) using combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG). The study presents an extended sample of 129 subjects (66 subjects have been previously reported): 19 patients with SCZ or schizoaffective disorder, 30 unaffected first-degree relatives of these SCZ patients, 13 obsessive-compulsive disorder (OCD) patients, 18 unaffected first-degree relatives of these OCD patients and 49 healthy subjects. In the DLPFC, cortical inhibition was significantly decreased in patients with SCZ compared to healthy subjects. First-degree relatives of patients with SCZ showed significantly more cortical inhibition than their SCZ probands. No differences were demonstrated between first-degree relatives of SCZ patients and healthy subjects. Taken together, these findings show that more studies are needed to establish an objective biological marker for potential diagnostic usage in severe psychiatric disorders.

Obsessive-compulsive disorder (OCD): Practical strategies for pharmacological and somatic treatment in adults

This narrative review gathers together a range of international experts to critically appraise the existing trial-based evidence relating to the efficacy and tolerability of pharmacotherapy for obsessive compulsive disorder in adults. We discuss the diagnostic evaluation and clinical characteristics followed by treatment options suitable for the clinician working from primary through to specialist psychiatric care. Robust data supports the effectiveness of treatment with selective serotonin reuptake inhibitors (SSRIs) and clomipramine in the short-term and the longer-term treatment and for relapse prevention. Owing to better tolerability, SSRIs are acknowledged as the first-line pharmacological treatment of choice. For those patients for whom first line treatments have been ineffective, evidence supports the use of adjunctive antipsychotic medication, and some evidence supports the use of high-dose SSRIs. Novel compounds are also the subject of active investigation. Neurosurgical treatments, including ablative lesion neurosurgery and deep brain stimulation, are reserved for severely symptomatic individuals who have not experienced sustained response to both pharmacological and cognitive behavior therapies.

A Pilot Test of the Additive Benefits of Physical Exercise to CBT for OCD

The majority of "responders" to first-line cognitive-behavioural therapy (CBT) and pharmacological treatments for obsessive-compulsive disorder (OCD) are left with residual symptoms that are clinically relevant and disabling. Therefore, there is pressing need for widely accessible efficacious alternative and/or adjunctive treatments for OCD. Accumulating evidence suggests that physical exercise may be one such intervention in the mood and anxiety disorders broadly, although we are aware of only two positive small-scale pilot studies that have tested its clinical benefits in OCD. This pilot study aimed to test the feasibility and preliminary efficacy of adding a structured physical exercise programme to CBT for OCD. A standard CBT group was delivered concurrently with a 12-week customized exercise programme to 11 participants. The exercise regimen was individualized for each participant based on peak heart rate measured using an incremental maximal exercise test. Reports of exercise adherence across the 12-week regimen exceeded 80%. A paired-samples t-test indicated very large treatment effects in Yale-Brown Obsessive-Compulsive Scale scores from pre- to post-treatment in CBT group cohorts led by expert CBT OCD specialists (d = 2.55) and junior CBT clinician non-OCD specialists (d = 2.12). These treatment effects are very large and exceed effects typically observed with individual and group-based CBT for OCD based on leading meta-analytic reviews, as well as previously obtained treatment effects for CBT using the same recruitment protocol without exercise. As such, this pilot work demonstrates the feasibility and significant potential clinical utility of a 12-week aerobic exercise programme delivered in conjunction with CBT for OCD.

Cross-disorder genome-wide analyses suggest a complex genetic relationship between Tourette's syndrome and OCD

OBJECTIVE

Obsessive-compulsive disorder (OCD) and Tourette's syndrome are highly heritable neurodevelopmental disorders that are thought to share genetic risk factors. However, the identification of definitive susceptibility genes for these etiologically complex disorders remains elusive. The authors report a combined genome-wide association study (GWAS) of Tourette's syndrome and OCD.

METHOD

The authors conducted a GWAS in 2,723 cases (1,310 with OCD, 834 with Tourette's syndrome, 579 with OCD plus Tourette's syndrome/chronic tics), 5,667 ancestry-matched controls, and 290 OCD parent-child trios. GWAS summary statistics were examined for enrichment of functional variants associated with gene expression levels in brain regions. Polygenic score analyses were conducted to investigate the genetic architecture within and across the two disorders.

RESULTS

Although no individual single-nucleotide polymorphisms (SNPs) achieved genome-wide significance, the GWAS signals were enriched for SNPs strongly associated with variations in brain gene expression levels (expression quantitative loci, or eQTLs), suggesting the presence of true functional variants that contribute to risk of these disorders. Polygenic score analyses identified a significant polygenic component for OCD (p=2×10(-4)), predicting 3.2% of the phenotypic variance in an independent data set. In contrast, Tourette's syndrome had a smaller, nonsignificant polygenic component, predicting only 0.6% of the phenotypic variance (p=0.06). No significant polygenic signal was detected across the two disorders, although the sample is likely underpowered to detect a modest shared signal. Furthermore, the OCD polygenic signal was significantly attenuated when cases with both OCD and co-occurring Tourette's syndrome/chronic tics were included in the analysis (p=0.01).

CONCLUSIONS

Previous work has shown that Tourette's syndrome and OCD have some degree of shared genetic variation. However, the data from this study suggest that there are also distinct components to the genetic architectures of these two disorders. Furthermore, OCD with co-occurring Tourette's syndrome/chronic tics may have different underlying genetic susceptibility compared with OCD alone.

Evidence for inhibitory deficits in the prefrontal cortex in schizophrenia

Abnormal gamma-aminobutyric acid inhibitory neurotransmission is a key pathophysiological mechanism underlying schizophrenia. Transcranial magnetic stimulation can be combined with electroencephalography to index long-interval cortical inhibition, a measure of GABAergic receptor-mediated inhibitory neurotransmission from the frontal and motor cortex. In previous studies we have reported that schizophrenia is associated with inhibitory deficits in the dorsolateral prefrontal cortex compared to healthy subjects and patients with bipolar disorder. The main objective of the current study was to replicate and extend these initial findings by evaluating long-interval cortical inhibition from the dorsolateral prefrontal cortex in patients with schizophrenia compared to patients with obsessive-compulsive disorder. A total of 111 participants were assessed: 38 patients with schizophrenia (average age: 35.71 years, 25 males, 13 females), 27 patients with obsessive-compulsive disorder (average age: 36.15 years, 11 males, 16 females) and 46 healthy subjects (average age: 33.63 years, 23 females, 23 males). Long-interval cortical inhibition was measured from the dorsolateral prefrontal cortex and motor cortex through combined transcranial magnetic stimulation and electroencephalography. In the dorsolateral prefrontal cortex, long-interval cortical inhibition was significantly reduced in patients with schizophrenia compared to healthy subjects (P = 0.004) and not significantly different between patients with obsessive-compulsive disorder and healthy subjects (P = 0.5445). Long-interval cortical inhibition deficits in the dorsolateral prefrontal cortex were also significantly greater in patients with schizophrenia compared to patients with obsessive-compulsive disorder (P = 0.0465). There were no significant differences in long-interval cortical inhibition across all three groups in the motor cortex. These results demonstrate that long-interval cortical inhibition deficits in the dorsolateral prefrontal cortex are specific to patients with schizophrenia and are not a generalized deficit that is shared by disorders of severe psychopathology.

Second generation antipsychotic-induced obsessive-compulsive symptoms in schizophrenia: a review of the experimental literature

Second generation antipsychotics (SGAs) have been implicated in the de novo emergence and exacerbation of obsessive-compulsive symptoms (OCS) in patients with schizophrenia. Among SGAs, clozapine, olanzapine, and risperidone are the most prominent agents associated with these sequelae, according to case reports. Comorbid OCS can impede recovery by compromising treatment benefits, medication compliance, and clinical prognoses. Previous reviews of SGA-induced OCS have predominantly focused on descriptive case reports, with limited attention paid toward experimental findings. To address this paucity of data, we sought to review the effects of SGAs on OCS in schizophrenia in the experimental literature, while addressing the role of different treatment (duration, dose, serum levels) and pharmacogenetic factors. Our findings suggest that clozapine confers the greatest risk of OCS in schizophrenia, with 20 to 28% of clozapine-treated patients experiencing de novo OCS, in addition to 10 to 18% incurring an exacerbation of pre-existing OCS. Clozapine can also yield full threshold obsessive-compulsive disorder (OCD), in some cases. Olanzapine is another high risk drug for secondary OCS which occurs in 11 to 20% of schizophrenic patients receiving olanzapine therapy. At this time, there is insufficient experimental evidence to characterize the effects of other SGAs on OCS. Despite some experimental support for the involvement of longer treatment duration and genetic factors in mediating drug-induced OCS, more research is needed to clearly elucidate these associations. Based on these results, schizophrenic patients should be routinely monitored for OCS throughout the course of SGA treatment, particularly when clozapine or olanzapine is administered.

Copy number variation in obsessive-compulsive disorder and tourette syndrome: a cross-disorder study

OBJECTIVE

Obsessive-compulsive disorder (OCD) and Tourette syndrome (TS) are heritable neurodevelopmental disorders with a partially shared genetic etiology. This study represents the first genome-wide investigation of large (>500 kb), rare (<1%) copy number variants (CNVs) in OCD and the largest genome-wide CNV analysis in TS to date.

METHOD

The primary analyses used a cross-disorder design for 2,699 case patients (1,613 ascertained for OCD, 1,086 ascertained for TS) and 1,789 controls. Parental data facilitated a de novo analysis in 348 OCD trios.

RESULTS

Although no global CNV burden was detected in the cross-disorder analysis or in secondary, disease-specific analyses, there was a 3.3-fold increased burden of large deletions previously associated with other neurodevelopmental disorders (p = .09). Half of these neurodevelopmental deletions were located in a single locus, 16p13.11 (5 case patient deletions: 0 control deletions, p = .08 in the current study, p = .025 compared to published controls). Three 16p13.11 deletions were confirmed de novo, providing further support for the etiological significance of this region. The overall OCD de novo rate was 1.4%, which is intermediate between published rates in controls (0.7%) and in individuals with autism or schizophrenia (2-4%).

CONCLUSION

Several converging lines of evidence implicate 16p13.11 deletions in OCD, with weaker evidence for a role in TS. The trend toward increased overall neurodevelopmental CNV burden in TS and OCD suggests that deletions previously associated with other neurodevelopmental disorders may also contribute to these phenotypes.

Pharmacogenetics of antidepressant treatment in obsessive–compulsive disorder: an update and implications for clinicians

Obsessive–compulsive disorder (OCD) is a chronic neuropsychiatric disorder with high genetic influence. Antidepressants such as serotonin reuptake inhibitors, are widely accepted as the first-line medications for OCD; however, approximately 50% of OCD patients show poor response. Personalized medicine utilizing genetic testing has recently received much attention because the variability of antidepressant response and tolerability are partly due to an individual’s genetic variations. This has led to researchers investigating the role of specific genetic factors on antidepressant response and utility of testing in the clinical realm. Genetic test panels are showing promise for guiding antidepressant treatment to improve outcomes in depression. This article will review the most recent findings in the pharmacogenetics of OCD and its related disorders. Promising results have been reported for several serotonergic and glutamatergic system genes and the cytochrome CYP450 liver enzyme genes, which appear to play an important role in OCD and antidepressant response.

Partitioning the heritability of Tourette syndrome and obsessive compulsive disorder reveals differences in genetic architecture

The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained by all SNPs for two phenotypically-related neurobehavioral disorders, obsessive-compulsive disorder (OCD) and Tourette Syndrome (TS), using GCTA. Our analysis yielded a heritability point estimate of 0.58 (se = 0.09, p = 5.64e-12) for TS, and 0.37 (se = 0.07, p = 1.5e-07) for OCD. In addition, we conducted multiple genomic partitioning analyses to identify genomic elements that concentrate this heritability. We examined genomic architectures of TS and OCD by chromosome, MAF bin, and functional annotations. In addition, we assessed heritability for early onset and adult onset OCD. Among other notable results, we found that SNPs with a minor allele frequency of less than 5% accounted for 21% of the TS heritability and 0% of the OCD heritability. Additionally, we identified a significant contribution to TS and OCD heritability by variants significantly associated with gene expression in two regions of the brain (parietal cortex and cerebellum) for which we had available expression quantitative trait loci (eQTLs). Finally we analyzed the genetic correlation between TS and OCD, revealing a genetic correlation of 0.41 (se = 0.15, p = 0.002). These results are very close to previous heritability estimates for TS and OCD based on twin and family studies, suggesting that very little, if any, heritability is truly missing (i.e., unassayed) from TS and OCD GWAS studies of common variation. The results also indicate that there is some genetic overlap between these two phenotypically-related neuropsychiatric disorders, but suggest that the two disorders have distinct genetic architectures.

Genome-wide association study of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a common, debilitating neuropsychiatric illness with complex genetic etiology. The International OCD Foundation Genetics Collaborative (IOCDF-GC) is a multi-national collaboration established to discover the genetic variation predisposing to OCD. A set of individuals affected with DSM-IV OCD, a subset of their parents, and unselected controls, were genotyped with several different Illumina SNP microarrays. After extensive data cleaning, 1465 cases, 5557 ancestry-matched controls and 400 complete trios remained, with a common set of 469,410 autosomal and 9657 X-chromosome single nucleotide polymorphisms (SNPs). Ancestry-stratified case-control association analyses were conducted for three genetically-defined subpopulations and combined in two meta-analyses, with and without the trio-based analysis. In the case-control analysis, the lowest two P-values were located within DLGAP1 (P=2.49 × 10(-6) and P=3.44 × 10(-6)), a member of the neuronal postsynaptic density complex. In the trio analysis, rs6131295, near BTBD3, exceeded the genome-wide significance threshold with a P-value=3.84 × 10(-8). However, when trios were meta-analyzed with the case-control samples, the P-value for this variant was 3.62 × 10(-5), losing genome-wide significance. Although no SNPs were identified to be associated with OCD at a genome-wide significant level in the combined trio-case-control sample, a significant enrichment of methylation QTLs (P<0.001) and frontal lobe expression quantitative trait loci (eQTLs) (P=0.001) was observed within the top-ranked SNPs (P<0.01) from the trio-case-control analysis, suggesting these top signals may have a broad role in gene expression in the brain, and possibly in the etiology of OCD.

Meta-analysis of association between obsessive-compulsive disorder and the 3' region of neuronal glutamate transporter gene SLC1A1

The neuronal glutamate transporter gene SLC1A1 is a candidate gene for obsessive-compulsive disorder (OCD) based on linkage studies and convergent evidence implicating glutamate in OCD etiology. The 3' end of SLC1A1 is the only genomic region with consistently demonstrated OCD association, especially when analyzing male-only probands. However, specific allele associations have not been consistently replicated, and recent OCD genome-wide association and meta-analysis studies have not incorporated all previously associated SLC1A1 SNPs. To clarify the nature of association between SLC1A1 and OCD, pooled analysis was performed on all available relevant raw study data, comprising a final sample of 815 trios, 306 cases and 634 controls. This revealed weak association between OCD and one of nine tested SLC1A1 polymorphisms (rs301443; uncorrected P = 0.046; non-significant corrected P). Secondary analyses of male-affecteds only (N = 358 trios and 133 cases) demonstrated modest association between OCD and a different SNP (rs12682807; uncorrected P = 0.012; non-significant corrected P). Findings of this meta-analysis are consistent with the trend of previous candidate gene studies in psychiatry and do not clarify the putative role of SLC1A1 in OCD pathophysiology. Nonetheless, it may be important to further examine the potential associations demonstrated in this amalgamated sample, especially since the SNPs with modest associations were not included in the more highly powered recent GWAS or in a past meta-analysis including five SLC1A1 polymorphisms. This study underscores the need for much larger sample sizes in future genetic association studies and suggests that next-generation sequencing may be beneficial in examining the potential role of rare variants in OCD.

The AmpliChip® CYP450 test and response to treatment in schizophrenia and obsessive compulsive disorder: a pilot study and focus on cases with abnormal CYP2D6 drug metabolism

AIM

Genetic factors can result in variance in drug metabolism enzyme function, which is one major mechanism impacting on interindividual variability in response and side effects. We therefore performed a pilot study to investigate genetic variants in the drug metabolizing enzymes CYP2D6 and CYP2C19.

METHODS

We evaluated 35 schizophrenic and 39 obsessive compulsive disorder (OCD) patients treated with various antipsychotics and antidepressants. Patients were assessed for treatment response and side effects. Genotyping for CYP2D6 and CYP2C19 was performed using the AmpliChip(®). Statistical analysis was performed using analysis of variance and Fisher's exact test. Cases of poor metabolizers (PMs) or ultrarapid metabolizers (UMs) were examined in further detail to assess medication outcomes.

RESULTS

Statistical analysis identified no overall significant association of CYP2D6 metabolizer status with treatment response or occurrence of side effects. Nonetheless, case reports of PM and UM individuals indicated lack of response and/or occurrence of side effects in most of these patients. A secondary analysis comparing OCD subjects with impaired 2D6 function to extensive metabolizers was significant (p=0.021).

CONCLUSION

Although not conclusive, there was some association between CYP2D6 impaired metabolic status and medication response. Our case reports suggest a potential clinical benefit of CYP genotyping for specific patients. Further validation of CYP2D6 and CYP2C19 testing in prospective, randomized trials is warranted.

Pharmacogenetics of obsessive-compulsive disorders

Genetic factors have been shown to influence occurrence and severity of several psychiatric disorders and also to modulate outcome to drug treatment. Obsessive-compulsive disorder (OCD) is a severe psychiatric condition with clear genetic roots; there is also some evidence to suggest that genetic factors may impact on response to drug treatment. Typically between 40 and 60% of patients are deemed nonresponders to antidepressant medication and clinical factors have only been modestly correlated with treatment response. Thus, identification of biological factors which may relate to treatment response could be extremely valuable in improving clinical outcome. In this article, we briefly review previous work regarding clinical and demographical factors associated with drug response in OCD, then focus on recent findings regarding candidate genes which may influence drug response, including those in the serotonin system, brain-derived neurotrophic factor and the glutamate transporter gene. The cytochrome system may also be highly relevant to drug response. Thus far, relatively few studies regarding the pharmacogenetics of OCD have been published, and therefore further investigation with functional analyses and consideration of environmental factors are warranted to facilitate clinical use of pharmacogenetic findings in the future.

Disgust recognition in obsessive-compulsive disorder: diagnostic comparisons and posttreatment effects

OBJECTIVE

To examine whether disgust recognition deficits are present and specific to obsessive-compulsive disorder (OCD), and the extent to which this deficit, if present, can be reduced in cognitive-behavioural therapy (CBT).

METHOD

Responses to the Pictures of Facial Affect (POFA) were examined in patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosed OCD (n = 20), panic disorder with agoraphobia (PDA; n = 15), and generalized social phobia (GSP; n = 15) and a second, independent OCD sample of treatment responders to CBT (n = 11).

RESULTS

There were significant and statistically large disgust recognition differences between the OCD group and comparison PDA and GSP groups. However, patients with OCD treated with CBT showed disgust recognition scores that were equivalent to the PDA and GSP groups, significantly better than the untreated OCD sample, and equivalent to scores from the original POFA nonaffected standardization sample.

CONCLUSIONS

These results provide support for the presence of disgust recognition impairment in OCD, and provide preliminary evidence that disgust recognition impairments may improve with treatment.

The GABA A-Receptor γ2 (GABRG2) Gene in obsessive-compulsive disorder

OBJECTIVE: The γ-aminobutyric acid type A (GABA A) system may be implicated in obsessive-compulsive disorder, based on its major role in modulation of anxiety and its function as the principal inhibitory neurotransmitter system in the cortex. In addition, glutamatergic/GABAergic mechanisms appear to play a role in the pathophysiology of obsessive-compulsive disorder, making the GABA A receptor-γ2 (GABργ2) gene a good candidate for susceptibility in this disorder. METHOD: 118 probands meeting DSM-IV criteria for primary obsessive-compulsive disorder and their available parents were recruited for participation in this study and informed consent was obtained. An NciI restriction site polymorphism in the second intron was genotyped and data was analyzed using the Transmission Disequilibrium Test. RESULTS: In total, 61 of the participating families were informative (i.e., with at least one heterozygous parent). No biases were observed in the transmission of either of the two alleles (χ2 = 0.016, 1 d.f., p = 0.898) to the affected probands in the total sample. CONCLUSION/DISCUSSION: While these results do not provide support for a major role for the GABA A receptor-γ2 in obsessive-compulsive disorder, further investigations of this gene in larger samples are warranted.

Psychological treatment of obsessive-compulsive disorder in patients with major depression: a pilot randomized controlled trial

OBJECTIVE

To examine the efficacy of cognitive-behavioural therapy (CBT) for obsessive-compulsive disorder (OCD) in patients with comorbid major depressive disorder (MDD).

METHOD

Participants (n = 29) diagnosed with comorbid OCD and MDD were randomized to receive standard CBT for OCD or integrated CBT that included an exclusive focus on treating MDD in the first phase of treatment and OCD in the second phase of treatment.

RESULTS

Both treatments resulted in statistically significant improvements in OCD and MDD symptoms. Treatment effects and recovery rates in the intent-to-treat sample were lower in both treatments, compared with past studies that excluded patients with MDD. However, among treatment completers, both treatments resulted in statistically significant and clinically meaningful improvements in OCD and MDD symptoms.

CONCLUSIONS

CBT holds promise as an efficacious treatment for people with comorbid OCD and MDD. The high treatment dropout rate with comorbid patients suggests that additional treatment strategies are required to enhance retention and optimize clinical outcomes.

Quality of life in treatment-seeking patients with obsessive-compulsive disorder with and without major depressive disorder

OBJECTIVE

To compare the quality of life of patients with obsessive-compulsive disorder (OCD) with and without depression comorbidity.

METHOD

Treatment-seeking outpatients (n = 56) with OCD (n = 28) or comorbid OCD and major depressive disorder (MDD) (n = 28), matched by age, sex, and antidepressant medication use, completed a multidimensional measure of quality of life.

RESULTS

Patients with comorbid OCD and MDD reported significantly greater decrements in their subjective feelings, social relations, and a composite measure of general activities (for example, overall well-being and life satisfaction) in comparison with patients with OCD without MDD. These differences were not owing to the presence of other Axis I comorbid disorders.

CONCLUSIONS

Treatments addressing depression comorbidity in the context of primary OCD are required to improve the quality of life of this severely affected population of OCD sufferers.

Glutamate receptor gene (GRIN2B) associated with reduced anterior cingulate glutamatergic concentration in pediatric obsessive-compulsive disorder

In this preliminary study, 16 psychotropic-naïve pediatric patients with obsessive-compulsive disorder (OCD) were studied using magnetic resonance spectroscopy (MRS) and genotyped for six candidate polymorphisms in two glutamate system genes. A significant association was identified between the rs1019385 polymorphism of the glutamate receptor, ionotropic, N-methyl-d-aspartate 2B (GRIN2B) and decreased anterior cingulate cortex (ACC) glutamatergic concentration (Glx) but not with occipital Glx. These results suggest that GRIN2B may be associated with Glx in the ACC, a region consistently implicated in OCD.

Obsessive-compulsive spectrum disorders: a review of the evidence-based treatments

OBJECTIVE

To provide a review of the evidence-based treatments for obsessive-compulsive spectrum disorders (OCSD), a group of conditions related to obsessive-compulsive disorder (OCD) by phenomenological and etiological similarities, the morbidity of which is increasingly recognized.

METHOD

Literature relating to the following disorders: body dysmorphic disorder, hypochondriasis, trichotillomania, onychophagia, psychogenic excoriation, compulsive buying, kleptomania, and pathological gambling, and published between January 1965 and October 2007, was found using PubMed. Included in this review were 107 treatment reports.

RESULTS

Serotonin reuptake inhibitors (SRIs) have shown benefits as first-line, short-term treatments for body dysmorphic disorder, hypochondriasis, onychophagia, and psychogenic excoriation, with some benefits in trichotillomania, pathological gambling, and compulsive buying. There are also suggested benefits for several atypical antipsychotics in disorders with a high degree of impulsivity, including trichotillomania and pathological gambling, and to a lesser extent, kleptomania and psychogenic excoriation. Cognitive-behavioural interventions have generally shown evidence for use as first-line treatment across the spectrum, with some variability in degree of benefit.

CONCLUSIONS

As in OCD, several conditions in the proposed OCSD benefit from SRIs and (or) cognitive-behavioural interventions. However, the treatment literature is generally limited, and more randomized controlled trials (RCTs) are needed to evaluate individual and combination treatments, for short-term use and as maintenance.

Obsessive beliefs in first-degree relatives of patients with OCD: a test of the cognitive vulnerability model

Cognitive models of obsessive-compulsive disorder (OCD) focus on the role of dysfunctional beliefs and appraisals in conferring risk to the onset and persistence of clinical obsessions. The origins of obsessive beliefs have been proposed to occur within a familial-based developmental context, although little research has examined this empirically. The aim of the present study was to examine the familial cognitive vulnerability for OCD by comparing scores on the Obsessive Beliefs Questionnaire (OBQ) [Obsessive Compulsive Cognitions Working Group (2005). Psychometric validation of the obsessive beliefs questionnaire and interpretation of intrusions inventory-Part 2. Factor analyses and testing of a brief version. Behavior Research and Therapy, 43, 1527-1542] between DSM-IV diagnosed OCD probands, their nonaffected first-degree relatives, and nonaffected controls. First-degree relatives scored significantly higher than controls on the OBQ domain tapping inflated responsibility and overestimation of threat. Further, relatives of early onset OCD probands scored significantly higher than controls on both the inflated responsibility and overestimation of threat domain and the domain tapping perfectionism and intolerance of uncertainty. The results are discussed in relation to the developmental context of cognitive-based vulnerabilities for OCD.

Glutamate system genes associated with ventral prefrontal and thalamic volume in pediatric obsessive-compulsive disorder

This pilot study was undertaken to determine if there was a significant association between specific glutamate system genes and regional volumes of interest implicated in the pathogenesis of obsessive-compulsive disorder (OCD). Volumetric magnetic resonance imaging (MRI) and genotyping of 7 polymorphisms in two genes, glutamate receptor, ionotropic, N-methyl-d-aspartate 2B (GRIN2B) and solute linked carrier, family 1, member 1 (SLC1A1) were conducted in 31 psychotropic-naïve pediatric OCD patients. The rs1805476 variant of GRIN2B was associated with left but not right orbital frontal cortex (OFC) (p=0.04) and right but not left anterior cingulate cortex (ACC) volume (p=0.02). The SLC1A1 rs3056 variant was associated with increased total (p=0.01), left (p=0.02) and right (p=0.02) thalamic volume. These results suggest that GRIN2B and SLC1A1 may be associated with regional volumetric alterations in OFC, ACC, and thalamus in children with OCD.

Glutamate transporter gene SLC1A1 associated with obsessive-compulsive disorder

CONTEXT

There is strong evidence from family and twin studies that genetic determinants play an important role in the etiology of obsessive-compulsive disorder (OCD). In the only genome scan of OCD to date that we are aware of, suggestive linkage was reported to the chromosomal region 9p24, a finding that was subsequently replicated. This region contains the gene encoding the neuronal glutamate transporter, SLC1A1. SLC1A1 represents an excellent candidate gene for OCD based on evidence from neuroimaging and animal studies that altered glutamatergic neurotransmission is implicated in the pathogenesis of this disorder.

OBJECTIVE

To determine whether sequence variants in SLC1A1 are associated with transmission of the OCD trait.

DESIGN

A family-based candidate gene association study.

SETTING

A specialized anxiety disorders outpatient clinic.

PARTICIPANTS

One hundred fifty-seven white probands with DSM-IV OCD recruited from consecutive referrals and their first-degree relatives (476 individuals in total).

INTERVENTION

Nine single nucleotide polymorphisms spanning SLC1A1 were genotyped. Single-locus and haplotype analyses were performed using the Family-Based Association Test and the Transmission Disequilibrium Test. Traits examined included DSM-IV OCD diagnosis and highest lifetime symptom severity as measured using the Yale-Brown Obsessive-Compulsive Scale. Correction for multiple comparisons was performed using permutation tests.

RESULTS

After correction for multiple comparisons, 2 variants, rs301434 (chi 2 = 12.04; P = .006) and rs301435 (chi 2 = 9.24; P = .03), located within a single haplotype block were found to be associated with transmission of OCD. Furthermore, a specific 2-marker haplotype within this block was significantly associated with OCD (chi 2 = 12.60; P = .005). This haplotype association was statistically significant in transmissions to male but not female offspring.

CONCLUSIONS

Although requiring replication in larger samples, these findings provide preliminary evidence that sequence variation in SLC1A1 is associated with susceptibility to OCD, particularly in males. Furthermore, these results provide support for the role of altered glutamatergic neurotransmission in the pathogenesis of OCD.

Tumor necrosis factor-alpha gene is not associated with obsessive-compulsive disorder

Dysregulation of the immune system has been suggested to play a role in the complex etiology of obsessive-compulsive disorder. In this context, tumor necrosis factor-alpha is considered an interesting candidate for genetic studies as overproduction of tumor necrosis factor-alpha, which may be genetically modulated, can exert neurotoxic effects and influence neural cell growth and proliferation. Moreover, the tumor necrosis factor-alpha gene is located on chromosome 6p21.3, a region that has been found to be weakly associated with obsessive-compulsive disorder in linkage studies. One functional polymorphism, G-308A, has been found within the gene.

Serotonin transporter promoter gain-of-function genotypes are linked to obsessive-compulsive disorder

A functional serotonin transporter promoter polymorphism, HTTLPR, alters the risk of disease as well as brain morphometry and function. Here, we show that HTTLPR is functionally triallelic. The L(G) allele, which is the L allele with a common G substitution, creates a functional AP2 transcription-factor binding site. Expression assays in 62 lymphoblastoid cell lines representing the six genotypes and in transfected raphe-derived cells showed codominant allele action and low, nearly equivalent expression for the S and L(G) alleles, accounting for more variation in HTT expression than previously recognized. The gain-of-function L(A)L(A) genotype was approximately twice as common in 169 whites with obsessive-compulsive disorder (OCD) than in 253 ethnically matched controls. We performed a replication study in 175 trios consisting of probands with OCD and their parents. The L(A) allele was twofold overtransmitted to the patients with OCD. The HTTLPR L(A)L(A) genotype exerts a moderate (1.8-fold) effect on risk of OCD, which crystallizes the evidence that the HTT gene has a role in OCD.

Serotonin transporter promoter gain-of-function genotypes are linked to obsessive-compulsive disorder

A functional serotonin transporter promoter polymorphism, HTTLPR, alters the risk of disease as well as brain morphometry and function. Here, we show that HTTLPR is functionally triallelic. The L(G) allele, which is the L allele with a common G substitution, creates a functional AP2 transcription-factor binding site. Expression assays in 62 lymphoblastoid cell lines representing the six genotypes and in transfected raphe-derived cells showed codominant allele action and low, nearly equivalent expression for the S and L(G) alleles, accounting for more variation in HTT expression than previously recognized. The gain-of-function L(A)L(A) genotype was approximately twice as common in 169 whites with obsessive-compulsive disorder (OCD) than in 253 ethnically matched controls. We performed a replication study in 175 trios consisting of probands with OCD and their parents. The L(A) allele was twofold overtransmitted to the patients with OCD. The HTTLPR L(A)L(A) genotype exerts a moderate (1.8-fold) effect on risk of OCD, which crystallizes the evidence that the HTT gene has a role in OCD.

The serotonin-1Dbeta receptor gene and severity of obsessive-compulsive disorder in women with bulimia nervosa

BACKGROUND

There is significant evidence that eating disorders have an important biological overlap with obsessive-compulsive disorder (OCD), though the specific mediators of this relationship remain unclear. Recent evidence suggests that the G861C polymorphism of the 5HT-1Dbeta receptor gene and the G allele in particular may play a role in OCD. We thus hypothesized that, among a heterogenous group of probands with bulimia nervosa (BN), this same G allele might predict the presence and/or severity of OCD pathology.

METHODS

165 consecutive female probands with BN were genotyped for the G861C polymorphism of the 5HT-1Dbeta receptor gene. Rates of full syndrome OCD, partial syndrome OCD and no OCD were compared across the three genotypic groups defined by this polymorphism.

RESULTS

45 out of 165 BN probands (27.3%) had either full or partial syndrome OCD. In the full sample, there was a significant difference in the distribution of the three diagnostic groups by genotype (chi2=10.07, df=4, p=.039). The G861C polymorphism did not strongly predict which probands had any vs. no OCD pathology. However, among the 45 probands with OCD symptoms, the G861C polymorphism did strongly differentiate full syndrome vs. partial syndrome OCD (chi2=9.26, df=2, p=.01; odds ratio for full syndrome OCD with GG genotype=7.69, 95% CI=1.45-40.9).

DISCUSSION

In women with BN, the G861C polymorphism of the 5HT-1Dbeta gene does not appear to be associated with the generation of OCD symptoms; however, it might directly or indirectly be associated with a modulatory effect on syndrome severity in probands otherwise predisposed to OCD. While preliminary and in need of replication in other samples, this is the first association study to suggest how a particular gene might influence OCD pathology in an eating disorder population.

The relationship between miscellaneous symptoms and major symptom factors in obsessive-compulsive disorder

The diverse symptomatology of obsessive-compulsive disorder (OCD) is being increasingly regarded as reducible to a few symptom dimensions. However, prevailing factor-analytically derived models of symptom structure omit a number of the well-recognized "miscellaneous" symptoms of OCD. This study sought to determine whether miscellaneous OCD symptoms, ascertained by the Yale-Brown Obsessive-Compulsive Scale symptom checklist, could be differentially and reliably predicted by four symptom factors (obsessions and checking, symmetry and ordering, contamination and cleaning, and hoarding) in two independent groups of individuals with OCD (n=381 and n=107). Logistic regression analyses were used to determine the association of each of the miscellaneous symptoms with the symptom factors; then a single confirmatory factor analysis was conducted to test the model of associations in the smaller sample. Sixteen (89%) of the 18 symptoms examined were reliably predicted by one (11 items) or two (5 items) of the factors, with obsessions and checking and symmetry and ordering emerging as foremost predictors. The expanded four-factor model showed good fit with data from the second sample. Results are conceptually meaningful, but suggest the inadequacy of groupings based solely upon overt behaviors. These findings may aid clinical understanding of OCD and be of value to studies using symptom factors to guide investigation of its causes and correlates.

Comorbidity and pathophysiology of obsessive-compulsive disorder in schizophrenia: is there evidence for a schizo-obsessive subtype of schizophrenia?

Epidemiologic and neurobiologic evidence suggests that patients with comorbid obsessive-compulsive disorder (OCD) and schizophrenia may represent a special category among patients with schizophrenia. Efforts to examine the neurobiology of this group have focused on neuroimaging studies and neuropsychologic testing. Convergent evidence suggests that there may be a specific pattern of neurobiologic dysfunction in this subgroup of patients accounting for symptom co-expression. This review indicates that future studies should distinguish among (1) apparent obsessive-compulsive symptoms (OCS) that occur only in the context of psychosis and that may overlap with psychotic phenomenology, representing a forme fruste of psychosis; (2) OCS occurring only in the prodromal phase of schizophrenia; (3) neuroleptic-induced OCS or OCD; and (4) OCS or frank OCD occurring concurrently with schizophrenia. We examine the evidence for a putative schizo-obsessive disorder and outline suggestions for identifying OCS in the presence of psychosis.